RILEY PRONUBA YUCCASKLLA, SUPPLEMBNT'y NOTES. 1 79 



wing-sheaths darker. When mature, and just before giving forth the moth, 

 the head, thorax, breast between the antenna;, and tip of abdomen, are 

 light brown ; the eyes, dorsal plates, and projections, darker brown ; the 

 wing-sheaths and interspaces between dorsal plates whitish ; and the sides 

 greenish. 



(^ (Fig. 3, /, dorsal view) distinguished generally by his somewhat 

 smaller size; by the dorsal projections not diminishing on joints 8-11, but 

 rather increasing in size; by the greater shortness of joint 11, and greater 

 length of joint 12 ; and by the apex not being so rounded, and not extend- 

 ing beyond the broad anal hornj' processes. At maturity the maxillary 

 pieces are somewhat flatter, owing doubtless to the fact that in § the spiny 

 cylindrical tentacles lie stretched nearly their whole length and cause them 

 to bulge more. 



Thus in the chn^salis state this insect is as abnormal and as ad- 

 mirably adapted to its conditions and wants as it is in the larva 

 and imago states. Sexual distinctions are very rarely observable 

 in chrj-salides ; but after I had learned to distinguish between 

 them I could readily separate the sexes in this case, and my judg- 

 ment was confirmed upon the issuing of the moths. By a series 

 of contortions, but more especially by alternate forward and back- 

 ward movements of the dorsal projections, this chrysalis easily 

 ascends to the surface of the ground, the cephalic spines serving 

 to open the end of the cocoon and the dorsal projections making 

 excellent levers by which it pries its way through the soil. 



I found it very difficult to hasten the natural process of devel- 

 opment, for notwithstanding that, in my anxiety to force a few^ 

 specimens, I kept them throughout the winter in a mean temper- 

 ature of about 80° F., I did not succeed in getting a chrysalis till 

 May 5th. As the blooming season of our filamentous Yuccas is 

 comparatively brief, and as all moths issuing before or after such 

 blooming ^vould be likely to die without issue, we find the habit 

 of developing at the proper season very strongly fixed. My first 

 moths issued (three of them, all forced) May 30th, leaving their 

 exuviae lying on the top of the ground. The cocoons out-doors, 

 and which are seldom more than five or six inches below the sur- 

 face of the ground, yet contain (June 2d), many of them, the 

 unchanged larva. 



In my fifth Report will be found evidence to show that in a 

 single case Yucca Jilamentosa has produced seed in England. 

 This exceptional fact indicates either that Pronuba occurs there ; 

 that other insects may occasionally be the pollenizers, or, as sug- 



